Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/06—Paper forming aids
  • D21H21/10—Retention agents or drainage improvers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/32—Polymerisation in water-in-oil emulsions

Definitions

• This invention relates to a process of preparation of microlatices dispersed in a continuous oil phase by polymerization (or copolymerization) in a microemulsion of the water-in-oil type of at least one water-soluble vinyl monomer and the use of these invert microlatices in the absorption and the retention of aqueous fluids.
• the water-soluble monomer or the mixture of monomers
• the proportions of components correspond to the monophase regions, also called microemulsions, of the monomer surfactant/oil/aqueous solution phase diagram.
• the monomer is trapped inside water-swollen micelles or else in the aqueous regions of a microemulsion of bicontinuous structure.
• These systems are optically transparent, thermodynamically stable and consequently lend themselves in particular to photochemical reactions.
• Such a process known in particular by the teaching of patent FR-A-2,524,895, has been applied in particular to acrylamide, acrylic acid and N-vinylpyrrolidone.
• the water-soluble monomer is photochemically or thermally polymerized in microemulsion.
• the method consists in initiating the polymerization photochemically, for example, by ultraviolet irradiation, or thermally with an initiator that is hydrophobic, for example, azobisisobutyronitrile, or hydrophilic, for example, potassium persulfate.
• the polymerization is photochemically performed very quickly, for example, in several minutes, quantitatively, and leads to the formation of microlatex whose particle radius is on the order of 15 nm.
• the surfactant used preferably is part of the class of anionic surfactants (such as sodium di-2-ethyl hexylsulfosuccinate) or of that of cationic surfactants (such as hexadecyl benzene-ammonium dimethyl bromide).
• a first problem that this invention proposes to solve therefore consists in determining the conditions under which this type of process could be usefully applied in the (co)polymerization of cationic water-soluble vinyl monomers, if necessary mixed with at least one nonionic or anionic water-soluble vinyl monomer.
• a second problem that this invention aims to solve consists in determining the preparation conditions under which the microlatices obtained are stable (thermodynamically) and optically transparent.
• Still another problem that this invention proposes to solve consists in determining the conditions under which the invert microlatices thus obtained could be used for the absorption and the retention of aqueous fluids, also as additives (flotation and drainage additives) in the production of paper pulp.
• a first object of this invention consists in an invert microlatex of at least one cationic water-soluble vinyl monomer, if necessary copolymerized with at least one anionic or nonionic water-soluble vinyl monomer.
• a microlatex which can be obtained in particular by the process described below in further detail, can have the following favorable properties and characteristics:
• polydispersity index defined as the ratio of the average diameter by weight of the polymer particles to their average diameter in number, between about 1.05 and 1.2
• a second object of this invention consists in a process of preparation of an invert microlatex such as defined above, comprising a first stage (a) of preparation of an invert microemulsion (of the water-in-oil type) and a second stage (b) in which the invert microemulsion obtained in stage (a) is subjected to polymerization conditions, characterized in that stage (a) consists in mixing the following components:
• the concentration of the cationic water-soluble vinyl monomer in aqueous solution (A) is generally between 5 and 80% by weight, preferably between 10 and 60% by weight.
• the liquid hydrocarbon present in oil phase (B) is preferably chosen from the aliphatic, linear, branched, or cyclic hydrocarbons, having 6 to 14 carbon atoms, or else from the aromatic hydrocarbons having 6 to 15 carbon atoms.
• nonionic surfactants usable according to this invention in particular are polyoxyethylene sorbitol hexaoleate, sorbitan sesquioleate, ethoxyl sorbitan trioleate, sorbitan trioleate and polyoxyethylene sorbitol monooleate as well as copolymers comprising at least two polymer components derived from liposoluble complex monocarboxylic acids and another residue polymer component of a water-soluble compound containing polyoxyalkylene patterns, said copolymers being such as those described in the European patent application published under no. 0,258,120 or their mixtures.
• Cationic water-soluble vinyl monomers entering into the scope of this invention are in particular unsaturated quaternary ammonium salts answering the general formula: ##STR1## in which:
• A is an oxygen atom or an NH group
• R 1 is a hydrogen atom or a methyl radical
• R 2 is a linear or branched alkyl radical having 2 to 4 carbon atoms
• R 3 , R 4 and R 5 are linear or branched alkyl radicals, or aryls, and
• X is chosen from halogen atoms and groups --C 2 H 5 --SO 4 and --CH 3 --SO 4 .
• salts are in particular methacryloyloxyethyltrimethylammonium chloride and acryloyloxyethyltrimethylammonium chloride.
• anionic water-soluble vinyl monomers usable according to this invention acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid and particularly their alkaline salts can be cited in particular.
• nonionic water-soluble vinyl monomers usable according to this invention acrylamide, methacrylamide and N-vinylpyrrolidone can be cited in particular.
• the cationic water-soluble vinyl monomer can be mixed in all proportions with at least one water-soluble vinyl monomer which is either anionic or nonionic such as defined above. However, in such mixtures, it is preferable that the proportion of the cationic water-soluble vinyl monomer be at least equal to 5% by weight.
• the proportion of the nonionic surfactant in the invert microemulsion and the choice of the HLB of this surfactant are two decisive elements for the effectiveness of the process according to the invention.
• a stable (thermodynamically) invert microemulsion generally cannot be obtained when the proportion of the surfactant in the mixture of components (A), (B) and (C) is less than 10% by weight.
• the choice of the HLB of the surfactant depends on the following four factors:
• the amount of surfactant required depends on the HLB of the latter and generally passes through a minimum value when the HLB increases. Since, for reasons of economic order, most often an effort is made to minimize the use of surfactant, this minimum value will also constitute an industrial optimum. It is therefore very important to determine in each case, as a function of the factors listed above, the HLB of the surfactant to be used.
• the following examples can be given: thus, when the methacryloyloxyethyltrimethylammonium chloride is polymerized alone, the oil phase consisting of cyclohexane, it is preferable to use a nonionic surfactant (or mixture) having an HLB between about 12.8 and 13.2.
• the methacryloyloxyethyltrimethylammonium chloride is copolymerized with acrylamide, the oil phase consisting of cyclohexane
• a nonionic surfactant or a mixture having an HLB between about 7.5 and 13, said HLB preferably being correlated to fraction by weight x of the chloride in the mixture by the relation:
• the determination of the HLB of the surfactant to be used for other monomers is within the scope of one skilled in the art.
• the temperature of the mixture be carefully controlled, because of the sensitivity to temperature of the invert microemulsions in the presence of nonionic surfactants. This influence of the temperature is all the more sensitive as the concentration in surfactant is closer to the minimum content required to obtain an invert microemulsion. To reduce the necessary content in surfactant and to be free to the maximum of the influence of the temperature on the stability of the invert microemulsions, the latter will be prepared as far as possible at a temperature as close as possible to that which will have been chosen for the polymerization.
• the invert microemulsion prepared during stage (a) is subjected to polymerization conditions which are:
• photochemical for example by ultraviolet irradiation, and/or
• a radical initiator that is hydrophobic (such as azobisisobutyronitrile) introduced with oil phase (B) or hydrophilic (such as potassium persulfate or ammonium) introduced with aqueous solution (A), or else in the presence of a redox system in which the persulfate is used in combination with at least one reducing agent chosen from polyhydrophenols, sodium sulfite and bisulfite, dimethylaminopropionitrile, diazomercaptans and ferricyanides.
• a radical initiator that is hydrophobic (such as azobisisobutyronitrile) introduced with oil phase (B) or hydrophilic (such as potassium persulfate or ammonium) introduced with aqueous solution (A), or else in the presence of a redox system in which the persulfate is used in combination with at least one reducing agent chosen from polyhydrophenols, sodium sulfite and bisulfite, dimethylaminopropionitrile,
• the polymerization is performed quickly and quantitatively and leads to the formation of stable and transparent microlatices containing a high content of water-soluble (co)polymer.
• the polymerization time is, for example, 5 to 260 minutes photochemically at room temperature, 5 to 360 minutes thermally (the time naturally being an inverse function of the temperature).
• the temperature usable during a polymerization thermally is generally between about 20° and 90° C.
• microlatices according to the invention are usable in a particularly effective way as flotation and drainage additives in the production of paper pulp, this application constituting the third object of this invention.
• crosslinking agents usable in this variant of the process according to the invention, there can be cited:
• di- or poly-esters of unsaturated mono- or poly-carboxylic acids with polyols such as esters of di- or tri-(meth)acrylic acids with polyols (such as ethylene glycol, trimethylolpropane, glycerol, polyoxyethyleneglycols, polyoxypropyleneglycols, etc.), unsaturated polyesters (that can be obtained by reaction with any of the above-mentioned polyols with an unsaturated acid such as maleic acid), esters of di- or tri-(meth)acrylic acid (that can be obtained by reaction of a polyepoxide with (meth)acrylic acid),
• esters of di- or tri-(meth)acrylic acids with polyols such as ethylene glycol, trimethylolpropane, glycerol, polyoxyethyleneglycols, polyoxypropyleneglycols, etc.
• unsaturated polyesters that can be obtained by reaction with any of the above-mentioned
• carbamylic esters that can be obtained by making polyisocyanates (such as toluene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethanediisocyanate, etc. and prepolymers containing an NCO group obtained by making such a diisocyanate react with the compounds containing active hydrogen atoms) react with monomers containing hydroxyl groups.
• polyisocyanates such as toluene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethanediisocyanate, etc. and prepolymers containing an NCO group obtained by making such a diisocyanate react with the compounds containing active hydrogen atoms
• esters are in particular those of di(meth)acrylic acids that can be obtained by making the above-mentioned diisocyanates react with the hydroxyethyl (meth)acrylate,
• di- or poly-allyl esters with polycarboxylic acids such as diallyl phtalate, diallyl adipate, etc.
• the compounds of the second above-mentioned type having at least one double polymerizable bond and at least one functional group reactive with at least one of the monomers are the ethylenically unsaturated compounds containing at least one group reactive with carboxyl, carboxyl anhydride, hydroxyl, amine or amide groups. Examples of these compounds are N-methylol(meth)acrylamide and glycidyl (meth)acrylate.
• 116 g of cyclohexane and 24 g of a mixture (having an HLB of 12.9) of polyoxyethylene sorbitan monooleate (TWEEN 80) and of sorbitan sesquioleate (ARLACEL 83) are mixed under agitation. Further, 30 g of methacryloyloxyethyltrimethylammonium chloride is dissolved in 30 g of distilled water, then this solution is added to the mixture of cyclohexane and surfactants.
• microemulsion is then irradiated under ultraviolet within a 500 ml reactor thermostatically controlled at 20° C. After an hour of polymerization, a clear microlatex is obtained having a limit viscosity (with a zero shearing gradient) of 6 centipoises, exhibiting a volume fraction of the dispersed phase equal to 37%, exhibiting a molecular weight of the polymer equal to 4.8 ⁇ 10 6 and a polydispersity index (such as defined above) equal to 1.1.
• Example 1 The operating process of Example 1 is reproduced by modifying only the amounts of the ingredients as follows:
• methacryloyloxyethyltrimethylammonium chloride 59.4 g.
• Example 1 The operating process of Example 1 is reproduced by modifying only the amounts of the ingredients as follows:
• methacryloyloxyethyltrimethylammonium chloride 40 g and by adding to the microemulsion 0.08 g of methylene bisacrylamide (crosslinking agent).
• the microlatex thus obtained is then treated in a way known in the art to recover the crosslinked cationic polymer.
• the latter is then dried in a ventilated oven at 60° C. for 24 hours then under partial vacuum (0.13 bar) at 30° C. After grinding into powder form, it is subjected to the following test:
• Pure water is added gradually to the polymer until saturation.
• the weight of absorbed water to reach saturation is then measured. The latter is equal here to 15 times the polymer weight.
• methacryloyloxyethyltrimethylammonium chloride 50 g.
• a transparent microlatex is obtained having a limit viscosity (with a zero shearing gradient) of 150 centipoises, exhibiting a volume fraction of the dispersed phase equal to 54%, presenting a molecular weight of the polymer (average by weight) equal to 12.4 ⁇ 10 6 and a polydispersity index equal to 1.1.
• Example 1 The operating process of Example 1 is reproduced by modifying the amounts of the ingredients as follows:

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• 1987
  • 1987-06-25 FR FR8708925A patent/FR2617172B1/fr not_active Expired - Fee Related
• 1988
  • 1988-06-17 ES ES88401511T patent/ES2058318T3/es not_active Expired - Lifetime
  • 1988-06-17 JP JP63505454A patent/JPH02503928A/ja active Pending
  • 1988-06-17 WO PCT/FR1988/000321 patent/WO1988010274A1/fr unknown
  • 1988-06-17 DE DE88401511T patent/DE3884302T2/de not_active Expired - Fee Related
  • 1988-06-17 EP EP88401511A patent/EP0299817B1/de not_active Expired - Lifetime
  • 1988-06-17 BR BR888807576A patent/BR8807576A/pt not_active Application Discontinuation
  • 1988-06-17 US US07/477,813 patent/US5171782A/en not_active Expired - Fee Related
  • 1988-06-17 AT AT88401511T patent/ATE94885T1/de not_active IP Right Cessation
  • 1988-06-27 CA CA000570501A patent/CA1309545C/fr not_active Expired - Fee Related

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